add osmo_tdef API, originally adopted from osmo-bsc T_def

Move T_def from osmo-bsc to libosmocore as osmo_tdef. Adjust naming to be more
consistent. Upgrade to first class API:
- add timer grouping
- add generic vty support
- add mising API doc
- add C test
- add VTY transcript tests, also as examples for using the API

From osmo_fsm_inst_state_chg() API doc, cross reference to osmo_tdef API.

The root reason for moving to libosmocore is that I want to use the
mgw_endpoint_fsm in osmo-msc for inter-MSC handover, and hence want to move the
FSM to libosmo-mgcp-client. This FSM uses the T_def from osmo-bsc. Though the
mgw_endpoint_fsm's use of T_def is minimal, I intend to use the osmo_tdef API
in osmo-msc (and probably elsewhere) as well. libosmocore is the most sensible
place for this.

osmo_tdef provides:

- a list of Tnnnn (GSM) timers with description, unit and default value.
- vty UI to allow users to configure non-default timeouts.
- API to tie T timers to osmo_fsm states and set them on state transitions.

- a few standard units (minute, second, millisecond) as well as a custom unit
  (which relies on the timer's human readable description to indicate the
  meaning of the value).
- conversion for standard units: for example, some GSM timers are defined in
  minutes, while our FSM definitions need timeouts in seconds. Conversion is
  for convenience only and can be easily avoided via the custom unit.

By keeping separate osmo_tdef arrays, several groups of timers can be kept
separately. The VTY tests in tests/tdef/ showcase different schemes:

- tests/vty/tdef_vty_test_config_root.c:
  Keep several timer definitions in separately named groups: showcase the
  osmo_tdef_vty_groups*() API. Each timer group exists exactly once.

- tests/vty/tdef_vty_test_config_subnode.c:
  Keep a single list of timers without separate grouping.
  Put this list on a specific subnode below the CONFIG_NODE.
  There could be several separate subnodes with timers like this, i.e.
  continuing from this example, sets timers could be separated by placing
  timers in specific config subnodes instead of using the global group name.

- tests/vty/tdef_vty_test_dynamic.c:
  Dynamically allocate timer definitions per each new created object.
  Thus there can be an arbitrary number of independent timer definitions, one
  per allocated object.

T_def was introduced during the recent osmo-bsc refactoring for inter-BSC
handover, and has proven useful:

- without osmo_tdef, each invocation of osmo_fsm_inst_state_chg() needs to be
  programmed with the right timeout value, for all code paths that invoke this
  state change. It is a likely source of errors to get one of them wrong.  By
  defining a T timer exactly for an FSM state, the caller can merely invoke the
  state change and trust on the original state definition to apply the correct
  timeout.

- it is helpful to have a standardized config file UI to provide user
  configurable timeouts, instead of inventing new VTY commands for each
  separate application of T timer numbers.

Change-Id: Ibd6b1ed7f1bd6e1f2e0fde53352055a4468f23e5

1 files changed, 292 insertions, 0 deletions

diff --git a/tests/tdef/tdef_vty_test_config_root.c b/tests/tdef/tdef_vty_test_config_root.c
new file mode 100644
index 00000000..138ac00a
--- /dev/null
+++ b/tests/tdef/tdef_vty_test_config_root.c
@@ -0,0 +1,292 @@
+/* Test implementation for osmo_tdef VTY configuration API. */
+/*
+ * (C) 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ * Author: Neels Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#define _GNU_SOURCE
+#include <getopt.h>
+#include <signal.h>
+#include <limits.h>
+#include <string.h>
+
+#include <osmocom/core/application.h>
+
+#include <osmocom/vty/command.h>
+#include <osmocom/vty/misc.h>
+#include <osmocom/vty/telnet_interface.h>
+
+#include <osmocom/core/tdef.h>
+#include <osmocom/vty/tdef_vty.h>
+
+#include <stdlib.h>
+
+#include "config.h"
+
+/* ------------------- HERE IS THE INTERESTING TDEF RELEVANT PART ------------------- */
+
+/* This example keeps several separate timer groups and offers 'timer' VTY commands at the root of the config node. See
+ * the tdef_vty_test_config_root.vty transcript test.
+ */
+
+static struct osmo_tdef tdefs_test[] = {
+	{ .T=1, .default_val=100, .desc="Testing a hundred seconds" },  // default is .unit=OSMO_TDEF_S == 0
+	{ .T=2, .default_val=100, .unit=OSMO_TDEF_MS, .desc="Testing a hundred milliseconds" },
+	{ .T=3, .default_val=100, .unit=OSMO_TDEF_M, .desc="Testing a hundred minutes" },
+	{ .T=4, .default_val=100, .unit=OSMO_TDEF_CUSTOM, .desc="Testing a hundred potatoes" },
+	{ .T=INT_MAX, .default_val=ULONG_MAX, .unit=OSMO_TDEF_M, .desc="Very large" },
+	{ .T=-23, .default_val=-15, .desc="Negative T number" },
+	{}  //  <-- important! last entry shall be zero
+};
+
+static struct osmo_tdef tdefs_tea[] = {
+	{ .T=1, .default_val=50, .desc="Water Boiling Timeout" },
+	{ .T=2, .default_val=300, .desc="Tea brewing" },
+	{ .T=3, .default_val=5, .unit=OSMO_TDEF_M, .desc="Let tea cool down before drinking" },
+	{ .T=4, .default_val=20, .unit=OSMO_TDEF_M, .desc="Forgot to drink tea while it's warm" },
+	{}
+};
+
+static struct osmo_tdef tdefs_software[] = {
+	{ .T=1, .default_val=30, .unit=OSMO_TDEF_M, .desc="Write code" },
+	{ .T=2, .default_val=20, .unit=OSMO_TDEF_MS, .desc="Hit segfault" },
+	{ .T=3, .default_val=480, .unit=OSMO_TDEF_M, .desc="Fix bugs" },
+	{}
+};
+
+static struct osmo_tdef_group tdef_groups[] = {
+	{
+		.name = "tea",
+		.desc = "Tea time",
+		.tdefs = tdefs_tea,
+	},
+	{
+		.name = "test",
+		.desc = "Test timers",
+		.tdefs = tdefs_test,
+	},
+	{
+		.name = "software",
+		.desc = "Typical software development cycle",
+		.tdefs = tdefs_software,
+	},
+	{}
+};
+
+enum tdef_vty_test_nodes {
+	TIMER_NODE = _LAST_OSMOVTY_NODE + 1,
+};
+
+/* This example puts 'timer' configuration commands directly at the root of the CONFIG_NODE.
+ * This TIMER_NODE is merely needed as a hook for the vty_write() command, but becomes an empty node in the VTY docs.
+ * It is possible to cheat around needing this if you choose to config_write_timer() in another root nodes' write cb.
+ * Another example using a 'network' subnode is \ref tdef_vty_test_config_subnode.c */
+static struct cmd_node timer_node = {
+	TIMER_NODE,
+	"%s(config-timer)# ",
+	1,
+};
+
+static int config_write_timer(struct vty *vty)
+{
+	osmo_tdef_vty_groups_write(vty, "");
+	return CMD_SUCCESS;
+}
+
+static void timer_init_vty()
+{
+	/* Again, this is merely to get a vty write hook, see above. */
+	install_node(&timer_node, config_write_timer);
+
+	osmo_tdef_vty_groups_init(CONFIG_NODE, tdef_groups);
+}
+
+/* ------------------- THE REST is just boilerplate osmo main() ------------------- */
+
+void *root_ctx = NULL;
+
+static void print_help()
+{
+	printf( "options:\n"
+		"  -h	--help		this text\n"
+		"  -d	--debug MASK	Enable debugging (e.g. -d DRSL:DOML:DLAPDM)\n"
+		"  -D	--daemonize	For the process into a background daemon\n"
+		"  -c	--config-file	Specify the filename of the config file\n"
+		"  -s	--disable-color	Don't use colors in stderr log output\n"
+		"  -T	--timestamp	Prefix every log line with a timestamp\n"
+		"  -V	--version	Print version information and exit\n"
+		"  -e	--log-level	Set a global log-level\n"
+		);
+}
+
+static struct {
+	const char *config_file;
+	int daemonize;
+} cmdline_config = {};
+
+static void handle_options(int argc, char **argv)
+{
+	while (1) {
+		int option_idx = 0, c;
+		static const struct option long_options[] = {
+			{ "help", 0, 0, 'h' },
+			{ "debug", 1, 0, 'd' },
+			{ "daemonize", 0, 0, 'D' },
+			{ "config-file", 1, 0, 'c' },
+			{ "disable-color", 0, 0, 's' },
+			{ "timestamp", 0, 0, 'T' },
+			{ "version", 0, 0, 'V' },
+			{ "log-level", 1, 0, 'e' },
+			{}
+		};
+
+		c = getopt_long(argc, argv, "hc:d:Dc:sTVe:",
+				long_options, &option_idx);
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'h':
+			print_help();
+			exit(0);
+		case 's':
+			log_set_use_color(osmo_stderr_target, 0);
+			break;
+		case 'd':
+			log_parse_category_mask(osmo_stderr_target, optarg);
+			break;
+		case 'D':
+			cmdline_config.daemonize = 1;
+			break;
+		case 'c':
+			cmdline_config.config_file = optarg;
+			break;
+		case 'T':
+			log_set_print_timestamp(osmo_stderr_target, 1);
+			break;
+		case 'e':
+			log_set_log_level(osmo_stderr_target, atoi(optarg));
+			break;
+		case 'V':
+			print_version(1);
+			exit(0);
+			break;
+		default:
+			/* catch unknown options *as well as* missing arguments. */
+			fprintf(stderr, "Error in command line options. Exiting.\n");
+			exit(-1);
+		}
+	}
+}
+
+static int quit = 0;
+
+static void signal_handler(int signal)
+{
+	fprintf(stdout, "signal %u received\n", signal);
+
+	switch (signal) {
+	case SIGINT:
+	case SIGTERM:
+		quit++;
+		break;
+	case SIGABRT:
+		osmo_generate_backtrace();
+		/* in case of abort, we want to obtain a talloc report
+		 * and then return to the caller, who will abort the process */
+	case SIGUSR1:
+		talloc_report(tall_vty_ctx, stderr);
+		talloc_report_full(root_ctx, stderr);
+		break;
+	case SIGUSR2:
+		talloc_report_full(tall_vty_ctx, stderr);
+		break;
+	default:
+		break;
+	}
+}
+
+static struct vty_app_info vty_info = {
+	.name		= "tdef_vty_test",
+	.version	= PACKAGE_VERSION,
+};
+
+static const struct log_info_cat default_categories[] = {};
+
+const struct log_info log_info = {
+	.cat = default_categories,
+	.num_cat = ARRAY_SIZE(default_categories),
+};
+
+int main(int argc, char **argv)
+{
+	int rc;
+
+	root_ctx = talloc_named_const(NULL, 0, "tdef_vty_test");
+
+	osmo_init_logging2(root_ctx, &log_info);
+
+	vty_info.tall_ctx = root_ctx;
+	vty_init(&vty_info);
+	osmo_talloc_vty_add_cmds();
+
+	timer_init_vty(); /* <---- the only tdef relevant init */
+
+	handle_options(argc, argv);
+
+	if (cmdline_config.config_file) {
+		rc = vty_read_config_file(cmdline_config.config_file, NULL);
+		if (rc < 0) {
+			fprintf(stderr, "Failed to parse the config file: '%s'\n", cmdline_config.config_file);
+			return 1;
+		}
+	}
+
+	rc = telnet_init_dynif(root_ctx, NULL, vty_get_bind_addr(), 42042);
+	if (rc < 0)
+		return 2;
+
+	signal(SIGINT, &signal_handler);
+	signal(SIGTERM, &signal_handler);
+	signal(SIGABRT, &signal_handler);
+	signal(SIGUSR1, &signal_handler);
+	signal(SIGUSR2, &signal_handler);
+	osmo_init_ignore_signals();
+
+	if (cmdline_config.daemonize) {
+		rc = osmo_daemonize();
+		if (rc < 0) {
+			perror("Error during daemonize");
+			return 6;
+		}
+	}
+
+	while (!quit) {
+		log_reset_context();
+		osmo_select_main(0);
+	}
+
+	talloc_free(root_ctx);
+	talloc_free(tall_vty_ctx);
+
+	return 0;
+}